JP3947192B2 - Underground continuous wall construction method - Google Patents

Description

  The present invention relates to an underground continuous wall method for creating an underground continuous wall by excavating an excavation hole for a retaining wall such as a soil column wall with an excavator.

  As construction of the soil column wall, an in-situ soil mixing method using a multi-axis excavator (Sile Mixing Wall, SMW) is known. As shown in FIGS. 19 and 20, the excavation shaft 5 is connected downward to a drive mechanism 4 including a hydraulic motor and a speed reducer, and a plurality of (5 in the drawing) excavation shafts 5 are arranged in parallel. It has been made.

  The excavation shaft 5 is provided with an excavation head 5a at the tip, and an excavation blade 5b that also serves as a stirring blade with screw blades interrupted in the middle. Although not shown, the excavation shaft 5 is a hollow shaft that allows a caking liquid such as cement milk to flow inside, and can be poured out from the discharge port of the excavation head 5a.

  The drive mechanism 4 is suspended from a top sheave 3 of a leader mast 2 standing on a base machine 1 such as a crawler with a wire while the excavation shaft 5 is connected. Furthermore, the drive mechanism 4 engages the curved bracket 6 provided on the back surface with the leader 7 provided along the leader mast 2. In the figure, reference numeral 8 denotes a neck-like steady rest provided at the lower end of the leader mast 2, and the excavation shaft 5 penetrates vertically.

  The excavation shaft 5 is rotationally driven by the drive mechanism 4 and excavation is carried out in the shape of a cone with the excavation head 5a. During the excavation, a caking liquid such as cement milk is discharged from the excavation head 5a, and the soil is in situ in the soil. 4 to form a soil cement wall body of the preceding element a as shown in FIG.

  Similarly, the soil cement wall body of the succeeding element b is completely wrapped with the soil cement wall body of the preceding element a (for example, a trajectory corresponding to one excavation shaft), and is continuously and integrally formed with the underground continuous wall. To do.

  And when using such a soil cement wall body as a retaining wall in underground construction of construction and civil engineering, as shown in FIG. 5, H-section steel is built as a stress bearing material (core material 9).

This core material 9 is suspended after a caking liquid such as cement milk is discharged and before the caking liquid hardens, and is suspended by a crane or the like. Drilling of the element is started (see, for example, Patent Document 1).
JP-A-10-131174

  When excavating with a multi-axis excavator, as shown in FIG. 4, the excavation track of each excavation shaft 5 is overlapped by one axis (overlapping), and when drilling to form the trailing element b, The leading element a is in a state where the core material 9 is embedded, and the core material 9 is immersed in the excavation hole.

  On the other hand, as the core material 10, a pressure receiving plate (FFU) made of a new material in which a hard urethane resin as shown in FIGS. This is because the FFU wall 10e is attached to the outside of the web of the H-shaped steel 10a by a tapered iron plate 10b, an adhesive iron plate 10c, and a fastening iron plate 10d, and the total thickness is made substantially equal to the width of the flange, and the glass long fiber reinforced plastic foam is used. Is the body.

  And this pressure plate is one-third lighter than concrete, has sufficient mechanical strength, has no water absorption / corrosion, has corrosion resistance / chemical resistance, and maintains the strength of the construction site for a long time. Have.

  When such a pressure receiving plate is used as the core material 10, the width of the core material 10 becomes wider as shown in FIG. 6 compared with the core material 9 made of the conventional H-shaped steel 9. High drilling accuracy is necessary (the drilling accuracy of conventional H-section steel is about 1/150 to 1/200, but when using a pressure receiving plate, the clearance becomes very narrow. Depending on the length, in some cases, a drilling accuracy of 1/1000 or more is necessary), which is a numerical value that is impossible with the current excavator.

  Moreover, even if high drilling accuracy is obtained, if an error occurs in the built core material 10 and the build accuracy is not ensured, the drilling of the succeeding element b as shown in FIG. For this reason, the excavation head 5a of the excavation shaft 5 may come into contact with the core material 10 of the element for the previous construction, so that there is a possibility that the hole cannot be drilled or the core material 10 is damaged.

  Furthermore, since the drilling order is constructed as a set of the preceding and succeeding two units, the core 10 to be built in the preceding element a previously drilled is timed for the subsequent construction time. Since the time has passed since the end of the previous drilling (usually about 1 to 4 hours from the end of the previous drilling), the insertability of the core material 10 is remarkably increased due to hardening of the cement and sedimentation of sand and gravel. Declined and workability is not good.

  In order to improve the insertability of the core material 10, in order to advance the timing of the core material 10 to be built in the preceding element a, if one-press (continuous) construction is performed as shown in FIG. Since the two core members 10 are immediately built after the hole is finished, and the drilling of the succeeding element b is started thereafter, the core member 10 of the preceding element a can be built at an early stage. It can prevent that the insertability of the core material 10 falls by sedimentation of sand and gravel.

  However, in this method, even if the core material 10 can be easily built, when drilling the succeeding element b, the drilling of the succeeding element b is performed in the direction of the softer leading element a of the ground previously applied. The part escapes (the direction indicated by the imaginary line in FIG. 8) and is drilled. As a result, the excavation head 5a of the excavation shaft 5 may come into contact with the core member 10 and break it.

  In addition, when one-pressing continuous construction is carried out, as shown in FIG. 9, the adjacent element is excavated immediately before the soil cement of the preceding element is hardened, so that the core material 10 built by pressurization at the time of excavation is pushed. It will be opened and will be placed diagonally.

  Further, as shown in FIG. 10, when the excavation shaft 5 of the succeeding element is pulled up, there is a disadvantage that the core material 10 previously placed by the negative pressure is drawn in the direction of the excavation head 5a.

  The object of the present invention is to eliminate the inconvenience of the conventional example, and even if high drilling accuracy cannot be obtained, or even if an error occurs in the construction of the core material, it is first constructed and constructed at the time of construction of the succeeding element. The core material can be prevented from coming into contact with the drilling head of the drilling machine of the subsequent drilling hole to the inserted core material, and the core material can be built immediately after drilling as a single-pressing work. To provide an underground continuous wall construction method that can improve the insertability of the core material, and even in such a case, it is possible to ensure the accuracy of laying and drilling the core material and shorten the construction period. It is in.

In order to achieve the above-mentioned object, the invention according to claim 1, the ground cement is excavated with a drilling machine for a column wall, and a soil cement wall of a preceding element is created. In the underground continuous wall construction method in which a continuous integral wall body is constructed by sequentially wrapping the above-mentioned element on the soil cement wall of the preceding element , a coreless soil is placed at a construction planned place where the wall body is constructed and this construction schedule At least one extra coreless soil is placed on each side of the location, the first leading element is created at the center of the centerless soil placement location, and the trailing element is placed on both sides of the first leading element. The gist is that it is semi-wrapped and is formed by one-push construction so that it spreads successively .

  According to the first aspect of the present invention, since the number of holes can be reduced by semi-wrapping the leading element and the trailing element, the hole adjacent to the core material placed in advance is drilled as a result. The number of drilling can be reduced, and the drilling accuracy and the accuracy of the core material can be improved. In addition, by placing a coreless soil in advance on each side of the planned construction site and one side of this planned construction site, the placement site of this coreless soil will be drilled again. Becomes a complete wrap, and can ensure water-stopping.

  In addition, since the trailing element is alternately pushed left and right in the order that it spreads sequentially on both sides around the first preceding element, the location where the core material is built and the drilling location of the next element are the first Move left and right around the preceding element. Therefore, the construction of the core material and the drilling can be performed at the same time, the construction period can be shortened, and the drilling does not affect the core material built in.

The invention according to claim 2 is characterized in that the excavation head of the excavator is formed in a bit shape facing inward as means for preventing the bit from contacting the core material of the adjacent preceding element. is there.

According to the second aspect of the present invention, even if the excavation head contacts the core material of the adjacent preceding element, the excavation head has a bit shape facing inward as a means for preventing the bit from contacting the core material. since the formation, not the bit is in direct contact with the core material, the breakage of the core material can be prevented. Even if such a means is provided in the excavation head, drilling with the excavation head is performed once with a coreless soil, and then drilling again with hard core. Can be installed without any problems.

  As described above, the underground continuous wall construction method of the present invention can be used even if high drilling accuracy cannot be obtained by placing a core-free soil in advance in the construction site and drilling this part again by the semi-lap construction method. In addition, even if an error occurs in the construction of the core material, the drilling head of the drilling machine of the subsequent drilling hole touches the core material that has been constructed and built at the time of the subsequent element construction, and the core material is damaged. In addition, the core material can be built immediately after drilling as a one-press operation, and the core material can be inserted more easily. Even in this case, the core material As a result, it is possible to ensure the accuracy of embedment and drilling, and to shorten the construction period.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram of a drilling sequence showing an embodiment of the underground continuous wall method of the present invention, and FIG. 2 is an explanatory diagram of a semi-lap method used in the underground continuous wall method of the present invention.

  The present invention is a case where the drilling diameter is φ900 mm and the drilling pitch is 1200 mm as a construction example, and the preceding drilling holes 11 are made at eight places as necessary. Next, the coreless soil 12 is placed in the order corresponding to the numbers 1, 2, 3, and 4 in FIG. 1 by complete lap construction at the location corresponding to the construction location of the core material 10 using the new material FFU. . In this way, the coreless soil 12 is placed in advance at a planned construction place where the core material 10 having a large width is placed.

  Next, the central position of the portion where the coreless soil 12 is placed as described above is drilled again, and the first preceding element 13a is constructed. In this case, immediately after the drilling is completed, a caking liquid such as cement milk is poured into the drilled part and the core material 10 is built before it solidifies. During this time, since the coreless soil 12 is driven on both sides of the preceding element 13a, it is possible to ensure water-stopping. After that, by the one-pushing construction method, the succeeding element 13b is constructed by re-drilling the place where the coreless soil 12 has been placed in advance at the position adjacent to the preceding element 13a (left adjacent in the illustrated example). To do.

  The period from the placement of the coreless soil 12 to the start of construction of the preceding element 13a (main construction start) is, for example, within one week. Repeat construction as many times as necessary.

  The succeeding element 13b is constructed by a semi-lap method, and the right end drilling of the succeeding element 13b and the left end drilling of the preceding element 13a are not completely lapped, and only a part of the adjacent portions overlap. It is. Therefore, when drilling the trailing element 13b, the excavation head is inserted into the preceding element 13a even if the drilling accuracy is not sufficient or the core material 10 is not sufficiently built in. There is no risk of contact with the core material 10.

  Further, since the coreless soil 12 is previously placed on the left end of the succeeding element 13b so that the soil to be drilled is made uniform, the drilling due to the difference in soil strength between the left and right portions of the succeeding element 13b. The escape (bending) of the part can be prevented, and the water stoppage of the part can be sufficiently secured.

  In order to further prevent the bit of the excavation head from coming into contact with the core material of the preceding element 13a when drilling the trailing element 13b, the shape of the excavation head 5a is such that the bit 5c facing inward is attached. Alternatively, as shown in FIG. 3, the ring 14 is wound around the excavation head 5a so that the core material 10 is not damaged even if the excavation head 5a contacts the core material 10.

  By the way, even if the ring 14 is mounted on the excavation head 5a, the drilling site is to drill the site where the coreless soil has been previously placed, so there is no problem even if the ground is hard. Is possible.

  Here, with respect to the preceding element 13a in which the core material 10 is built after the drilling is completed, the drilling of the subsequent element 13b is not performed on the day of the core material 10 being built. This is because if the soil cement injected into the drilling hole is drilled next without solidifying, the soil cement flows due to negative pressure or pressurization during drilling, so that the core material 10 is accurately built. This is because it moves with the flow of the soil cement (occurrence of secondary error). Therefore, in order to prevent the occurrence of this secondary error, no drilling (construction) is performed next to the erection completion site during the day.

  If the drilling of the succeeding element 13b on the left side of the preceding element 13a is completed, the element 13c on the right side of the preceding element 13a is drilled. At the same time, the trailing element 13b builds the core material 10. Since the core material 10 can be built immediately after drilling, the insertability is good.

  Thus, since the succeeding element 13b and the next construction element 13c are in the left and right separated positions with the central preceding element 13a in the middle, the erection of the core material 10 of the succeeding element 13b and the next element There is no problem even if the drilling of 13c is performed simultaneously. Therefore, the construction period can be shortened.

  In this order, the succeeding elements are sequentially constructed by one-press construction alternately on the left and right by the semi-lap method with the center leading element 13a as the center. And, by adopting the semi-lap method, the total number of holes can be reduced, so the number of times of excavating the side of the core material 10 that has been previously built is reduced, and the possibility that the excavation head 5a contacts the core material 10 is reduced. Can be reduced.

It is explanatory drawing which shows the drilling order in the underground continuous wall construction method of this invention. It is explanatory drawing of the semi-lap construction method used with the underground continuous wall construction method of this invention. It is a front view which shows an example of the excavation head used with the underground continuous wall construction method of this invention. It is explanatory drawing of a normal lap construction method. It is a top view which shows the built-in state at the time of using H-section steel for a core material. It is a top view which shows the embedding state at the time of using a new material for a core material. It is explanatory drawing which shows the drilling order by a normal lapping method. It is explanatory drawing which shows the hole-drilling order at the time of carrying out a pressing work by the normal lapping method. It is a front view which shows the secondary error generation | occurrence | production situation of the erection accuracy of the core material at the time of excavation by a multi-axis construction method. It is a front view which shows the secondary error generation | occurrence | production situation of the embedding precision of the core material at the time of the pulling by a multi-axis construction method. It is a top view which shows the embedding state at the time of using the core material by a new material. It is a side view of the core material by a new material. It is a front view of the core material by a new material. It is the sectional view on the AA line of FIG. 13 of the core material by a new material. It is the BB sectional drawing of FIG. 13 of the core material by a new material. It is CC sectional view taken on the line of FIG. 13 of the core material by a new material. It is the DD sectional view taken on the line of FIG. 13 of the core material by a new material. It is the EE sectional view taken on the line of FIG. 13 of the core material by a new material. It is a front view of the multi-axis excavator used with the underground continuous wall construction method of this invention. It is a side view of the multi-axis excavator used with the underground continuous wall construction method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base machine 2 Leader mast 3 Top sheave 4 Drive mechanism 5 Drilling shaft 5a Drilling head 5b Drilling blade 5c Bit 6 Curved bracket 7 Leader 8 Anti-rest 9 Core material 10 Core material 10a H-shaped steel 10b Tapered iron plate 10c Adhesive iron plate 10d Tightening Iron plate 10e FFU wall 11 Pre-drilled hole 12 Coreless soil
13a Leading element 13b Trailing element
13c Element 14 Ring

Claims (2)

The ground is excavated by the excavator for the column wall, and the soil cement wall of the preceding element is formed. Next, the soil cement wall of the succeeding element is sequentially wrapped with the soil cement wall of the preceding element, and the continuous integral wall body. In the underground continuous wall construction method, a coreless soil is cast at the planned construction site where the wall body is constructed, and at least one extra coreless soil is placed at both sides of the planned construction site. The first leading element is formed at the center position of the uncored soil placing place, and the trailing element is semi-wrapped on both sides of the first leading element and is formed by one-pressing construction so as to continuously spread. underground continuous wall method according to claim. 2. The underground continuous wall according to claim 1, wherein the excavating head of the excavator is formed in a bit shape facing inward as a means for preventing the bit from contacting a core material of an adjacent preceding element. Construction method.

Images